(a) Field of the Invention
The invention relates to a system and a method for modulating backlight for a display device.
(b) Description of the Related Art
In order to reduce the power consumption of an electronic device having a liquid crystal display (LCD) panel, a typical method is to adjust the brightness of a backlight module. However, a conventional power-saving design of manually adjusting backlight usually affects the display quality. Besides, a viewer may feel uncomfortable when the backlight is adjusted to result in too bright or too dark display.
Referring to FIG. 9, Japan patent publication no. 08-201812 discloses an LCD display device 100 where backlight is dynamically adjusted to improve the conventional power-saving design. The LCD display device 100 includes a display control unit 102, an LCD display screen 104, a backlight module 106, an average brightness detecting unit 108 and a backlight control unit 110. When the average brightness detecting unit 108 detects the average brightness level of an image being at a high level, the backlight control unit 110 is used to reduce the brightness of the backlight module 106. Such design may avoid a too bright or too dark display of the LCD display screen 104 and enhances the contrast between a dark screen and a bright screen. However, when the average brightness level is at a low level, some light may leak from the backlight module 106 as a black frame is displayed to cause loss of true black and hence deteriorate the display quality.
FIG. 10 shows an improved design of backlight brightness adjustment, where backlight is dynamically adjusted according to frame signals. As shown in FIG. 10, in a backlight processing system 200, frame signals are fed into and then processed by a display control unit 202, an average brightness detecting unit 204 and a peak brightness detecting unit 206. The display control unit 202 converts the format of frame signals to enable the frame signals to be displayed on the LCD display screen 208. The average brightness detecting unit 204 calculates average brightness of the frame signals and then outputs an average brightness signal AVE serving as a backlight adjustment parameter to the backlight control unit 212. The peak brightness detecting unit 206 performs peak calculation on pixel data of different frame signals to acquire a peak signal PEK that is transmitted to the backlight control unit 212. The backlight control unit 212 adjusts the brightness of the backlight module 214 according to the average brightness signal AVE and the peak signal PEK. Though such design may dynamically adjust the brightness of a displayed frame to achieve power-saving, the displayed frame seen by human eyes is relatively dark and fails to convey the original visual effect.